Mixture control device



Nov. 21, 1961 F. BARFOD 3,009,688

MIXTURE CONTROL DEVICE Original Filed April 14, 1954 2 Sheets-Sheet l HIM Z 90 INV EN TOR.

FR EDERIK BAR/0D ATTORNEY.

Nov. 21, 1961 F. BARFOD 3,009,688

MIXTURE CONTROL DEVICE Original Filed April 14, 1954 2 Sheets-Sheet 2 T1155 FREDERIK gZ R F- ED.

BY gm z. W

ATTORNEY.

United States Patent 3,009,688 MIXTURE CONTROL DEVICE I Frederik Barfod, Detroit, Mich.,' assignor to The Bendix Corporation, a corporation of Delaware Original application Apr. 14, 1954, Ser. No. 423,183, now "Patent No. 2,910,280, dated'Oct. 27, 1959. Divided and this application Mar. 23, 1959, Ser. No. 801,386 4 Claims. (Cl. 261-69) This invention relates to charge forming devices for internal combustion engines and more particularly to mixture controls therefor for regulating or controlling the amount of fuel supplied to an engine as a function of atmospheric pressure, density or manifold pressure. The instant mixture control is particularly adapted for use with a charge forming device of the injection type disclosed in my copending. US. application Serial No. 377,519 filed August 31, 1953, on which Patent No. 2,786,460 issued March 26, 1957, and is an improvement over the mixture controladisclosed therein; Thepresent application is a division of my copending application Serial No. 423,183 filed April 14, 1954, now US. Patent No. 2,910,280 issued October 27, 1959.

It is an object of the invention to provide a mixture control device, for a fuel injection system which automatically regulates the fuel-air mixture ratio in response to changes in an engine operating condition and atmospheric pressure or density.

Another object of the invention is to provide a mixture control for a fuel injection system which maintains a substantially constant fuel-air mixture ratio ,as a function of atmospheric air pressure or density and which auto matically regulatesthe fuel-air mixture ratio between predetermined limits as a function of manifold vacuum.

, A further object of the invention is to provide a simple compact mixture control fora fuel injectorin which the fuel-air mixture ratio is regulated in response to changes in altitude and an engine operating condition, such as,

intake manifold pressure.

Other objects and advantages will 'belreadily apparent to one skilled in the art from the following description; taken in connection with the accompanying drawings in which: 7 FIGURE 1 is a diagrammatic sectional view of a fuel injector embodying the invention; I

FIGURE Zis a diagrammatic sectional view of the mix- I ture control shown in FIGURE 1 connected to an induc-' tion passage having a supercharger; and

'FIGURE 3 is a partial v1ew 1n section of a modified form of the invention.

-' With reference. toFIGURE 1, in which muchxof the structure is-as shown in mycopending application Serial No. 377,519,; now Patent No- 2,786,460; a gear pump 10 having, an inlet, 12 and an 'outlet:14=i's-adapted to be driven :by an engine (not shown) through a'shaft 16.

Fuel undersubstantially constant "pressureuis supplied froma source- (not shown) to the inlet Hand is discharged through outlet 14 at -a 'pr'essurevarying as a functionof engine speed. A fuel injection' -pump is shown at 20. having an inlet 22;in communication with the outlet of the gear pump through a fuel metering control-generally shown at 24. The fuel dischargedby the gear pump is metered by the control unit '24 as a,

function of manifold pressureand, optionally, ambient air temperature. A portion :of thisfuel, depending on altitude and engine operating conditions as reflected by manifold pressure and/or ambient air temperature is bypassed to the inlet of. the gear pump. A quantity of metered fuel depending on the characteristics of the particularengine being supplied by my fuel feeding system is. i

also by-passed to the inlet of the gearipump. The re mainder of the metered fuel flows to the injection pump which delivers the fuel to the manifold of the engine in i "ice ed ona wobble plate 44 which is secured to shaft 16..

Conduit 46 containing check valve 48, is provided to connect each discharge port 50 with a nozzle 52 located in the manifold 54. Although the nozzles as shown, are discharging into the manifold, it is to be understood that the nozzles could equally well be located in the cylinder wall to discharge directly into eachof the cylinders of the engine.

A throttle body 60 with a throttle valve 62 mounted therein is secured to the manifold by suitable bolts (not shown). As shown in FIGURE 2, a supercharger 64,,

of conventional design, may also be included in the induction passage. p

A mixture control unit forms a part of the fuel metering unit '24 and is connected through a conduit 72 to the induction passage on the engine side of the throttle anterior to the supercharger, if included. The mixture control unit 70 regulates valve 74 in passage 76 controlling the amount of fuel by-passed from the gear pump outlet 14 to the inlet 12 through passages 76, 78, 80, 82, 84 and 85. A pressure equalizing valve located in conduit 78 is freely reciprocable therein between retaining' members 92 to control the communication between conduit 78 andpassage 80. I

A quantity of metered fuel depending on the peculiar characteristics of the enginebeing supplied by the fuel feeding system, is by-passed through a second by-pass consisting of passages 94, 96,98, 100, 102, 8 2, 84 and 85. Pressure equalizing valve 90'separates passage 78 of valve'114 and unit 116 may be omitted from the meteringcontrol if desired.

A power enrichment systemis provided at numeral 140, consisting of a power enrichment jet 142 connecting conduit 94 with conduit 78. Thepower enrichment jet is controlled-by avalve 144 which on one side is subjected to gear pump outlet pressure through conduits 94 and 1 46 and on the other side to a force of the spring 148 and the pressure in conduit 78'. At low and medium speeds the jet is open thereby by-passing a portion of the fuel from conduit 94 to the conduit 78 and causing the quantity'of fuel delivered to the inlet'22 of the injection pump to'be' decreased. 'At' high speed the gearpump discharge pressure is sufficient to move valve 144' to a position to close the jet, thereby cutting off the by-pass and causing an increase in the quantity of fuel delivered to the injection pump.

The mixture control unit 70, as shown in FIGURES l and2, includes a housing 160, a partition-member 162 threadedly received in said housing and a cover 164 secured to the partition member by suitable bolts 166. Diaphragm 1'68, marginally clamped between the cover 7 and partition member, divides the interior of the unit into two chambers, and 172, which through conduit 72 i and port 174 are subjected to manifold pressure and atmospheric pressure respectively. Located in chamber 17 0,

bellows 176 is connected at one end to diaphragm 168 Patented Nov. 21, 1961 The pumping cylinders are preferably 3 by a rod 178 and at the other end to valve 74 by a linkage 180. A tubular member 179 secured to an interior end wall of the bellows 176 slidably receives aball ended rod 181 secured to the opposite interior end wall of the bellows to provide internal support for said bellows.

Bellows 176 maybe filled with a pressure and temperature responsive fluid, nitrogen, for example; or it may be evacuated and rendered substantially insensitive to temperature. In the latter instance a spring 182 is located in the interior of the bellows to provide additional internal support therefore. The responsiveness of the bellows to ambient air temperature, in any case, is in part determined by the location of the'mixture control unit with respect to the engine being supplied by the fuel feeding system. In some installations temperature control in addition to that provided by the bellows may be desired, in which case the previously described temperature responsive unit 116 is used. Temperature control may be provided by either bellows 176 or unit 116, alone or in combination. It has been discovered that in some installations, such as are used on motor vehicles, that nospecial correction for ambient air temperature variations is necessary and in such an installation unit 116 is omitted and bellows 176 is evacuated with a calibrated spring 182 inserted in the interior thereof as previously described. t

The bellows 176 functions to regulate the quantity of fuel supplied to the manifold to maintain a substantially constant fuel-air mixtureratio supply to the engine. With the bellows evacuated, and the mass of air delivered to the manifold decreasing as a result of a decreasein atmospheric and/or manifold pressures, the pressure in chamber 170 decreases whereupon spring 182 urges linkage 180 in a direction to open valve 74 causing an increase in the amount of fuel by-passed with a consequent reduction in quantity of fuel discharged from the nozzles 52 whereby the fuel-air mixture ratio is maintained substantially constant.

Additional meansis included in the mixture control unit 70 to vary the fuel-air mixture ratio between predetermined limitsto automatically provide either a rich or power fuel-air ratio oran economy cruising fuel-air ratio in response to changes inengine operating conditions reflected, as forexample, inchanges in manifoldpressure. This means includes a'spring183 reactin'gbetween partition member 162 and a retainer 184 centrally clamped to diaphragmT1'68,.said spring urges the diaphragm v168, rod 178, bellows 17.6 and linkage 180 in a direction to move valve 74 towards closed position to ,increase the fueldelivered to injection pump 20 and thus enriches the fuel-air ratio to provide a power mixture. The force of spring 183 is opposed by manifold vacuum acting on diaphragm .168 through ports186, chamber 170.and conduit 72. Wheneverthe differential between the pressures on oppositesides of the diaphragm, i.e. the difference between atmospheric pressure in chamber 172 andmanifold pressure in .170, exceeds a predetermined value. the force of spring 183 will;be overcome andvalve 74 will be moved to or held in apositionto obtain an economy or cruisingfuel-air mixtureratio. The limits of the. fuelairmixture ratio are established by thelength of travel ofdiaphragm .168 which islimited in one direction by the abutmentof spring retainer .184 against ,partition member 162 and in the other direction by the abutment of bellows 176. against said partition member.

In the embodiment shown in FIGURE 3, the mixture control unit 70a includes a housing 200 having a cupshaped end member- 202 threadedly received therein. A hollow piston 204 connected to valve 74 through a linkage 205 is slidably disposed in the interior of the housing and forms a movable wall between chambers 206 and 208 which through conduit72 and ports 210 are subjected to manifold and atmospheric pressures respectively. Bellows 212 is positioned in chamber208 with one end secured to member 202, as by brazing, and is connected at the other'end to rod 214 which is supported in a spider 216 mounted in the interior of piston 204. Rod 214 is urged into abutting engagement with said piston by a spring 218 reacting between said spider and a spring retainer 220. Rod 214 projects into the interior of bellows 212 and is provided with a terminal ball 221 which reciprocates in a tubular member 22210 give internal support to said bellows. [Spring224 is positioned between a retainer 226 and the rod end of the bellows to assist in adapting the bellows for .use in different installations.

In the operation of the embodiment shown in FIG- URES 1 and 2, fuel under a pressure varying as a function of an engine speed is discharged by gear pump 10 to metering restriction 112 and valve '74 through conduits 94 and 76 respectively. The size of mete'ring'restriction 112 maybe fixed or may be varied by' a valve 114 as a function of manifold air'te'rnperature by the temperature unit 116. In either event, aportion of the' mete'red fuel, the amountof which depends on the operating characteristics of the particular engine being supplied'by thefuel system, is by-passed through passages 96, 98, 100, 102, and 82, 84 and 85. The remainder of the metered fuel passes through conduit 110 to inlet 22 of the'injection pump where rotary valve 26 measures the amount of fuel delivered to each pump cylinder"2.

A portion of the fuel discharged by the gear pump is by-passed through a second bypass consisting of passages 78, 80, 82, 84 and'85. The amount'of fuel thus by-passed is controlled by valves 74,. 90 and 144.

Valve 74 is controlled by mixture control unit 70 through linkage 180 connected directly to bellows 176 which is responsive to changes in manifold vacuum and/ or ambient air temperature. Movement of valve 74 in response to move'ment'iof bellows 176 regulatesflthe amount of'fuel by-passed as alfunctionofthe mass of'air entering the manifold so ,as to maintain the fuel-air ratio substantially constant. Valve ,74is further regulated'by diaphragm168whichis connected to bellows .176 by rod 178. .Spring 183urgesthe diaphragm 168 in ,a direction to close valve 74 to 'd'ecrease the amount of fuel by passed through passage 'and cause an increase in the amount of fuel ,deliveredto the engine .andthus produce a power or rich .fuel-air mixtureratio'. Whenthe absolute manifold pressure,dropsbelow atmospheric pressure ,a predetermined amount, diaphragm 168 will be moved in pp s t on o s rin 5 t mor salv t ward ope position to increase the amolmtQfifuel by-passed through passage80 and thereby decrease the :fueldeliveredjto the engineto produce aneconomy or cruising -fuel-airmixture ratio. Valve downstream of valve ,74is responsiveto the pressure differential-between passage .78iandi98 tends to equalize said pressures.

During low andmedium speeds power enrichment jet 142 is open permitting fuel to how h'om passage .94 to passage 78 and resulting in a decrease in the'amourit of fuel deliveredto the engine. During high speed operation howevenfthe pressure offuel in theconduit 46, which varies as a function of engine speed is sutficient'to move 'valve 144 to close jet' 142 and thereby eifect'an' increased flow to metering restriction 112'.

In operation of'the embodiment shown in 3, the mixture control unit 7011, as in'the previous e'inbodiment, regulates the fuel-air mixture'ratio in response to changes in atmospheric pressure and engine operating conditions as reflected by manifold pressure. Whenftlie absolutemanifold pressure in chamber 206 drops below atmospheric pressure a predeterniinedar'nount, piston 204 will be moved in oppositio'h to spring-218 in "a direction to open valve 74 andthereby decrease the ar'n ount of, fuel supplied to the engine to produce an' economy or eruising fuel-air mixture ratio. Whenithe'presjsuredifferential between chambers 206 and 208,110 longerexceeds said predetermined amount, spring 218 will move valve'toward closed position to increase the. fuel supply to the engine and thereby produce a power or rich fuel-air mixture ratio. Bellows 212 is subjected directly to atmospheric pressure and has a lost motion connection with piston 204 through rod 214. Belows 212 functions, as does bellows 176, to regulate the quantity of fuel supplied to the manifold to maintain a substantially constant fuel-air mixture ratio supply to the engine.

From the above description it will be readily apparent to those skilled in the art that many changes or arrangements of parts may be'made without departing from the spirit of my invention.

I claim:

1. A mixture control for a fuel feeding system having control means and an induction passage, comprising a housing, a piston in said housing dividing the interior thereof into two chambers, means'connecting one of said chambers with said induction passage, atmospheric openings in the Wall of the other chamber, a pressure responsive bellows in said last mentioned chamber, a rod secured to said bellows and having a lost motion connection with said piston, a spring urging said rod into abutting engagement with said piston, and means adapted to' connect said piston and'said control means.

i 2. A mixture control for a fuel feeding system having control means and an induction passage, comprising a housing, a movable wall in said housing dividing the interior thereof into two chambers, an atmospheric opening in the wall of one chamber, means connecting the other of said chambers with the induction passage, an element in said first mentioned chamber responsive to variations in air density, means including a lost motion means connecting said element and movable Wall, and means adapted to connect said wall and said control means.

3. A mixture control for a fuel feeding system having control means and an induction passage with a throttle therein, comprising a housing, a piston in said housing dividing the interior thereof into two chambers, means connecting one of said chambers with the induction pas sage downstream of the throttle, means connecting the other of said chambers to the atmosphere, a, bellows re--;

sponsive to ambient air pressure, retaining means connected to said bellows, spring means engaging said retaining means and said piston to form an operative connection therebetween, and means adapted to connect said'piston and said control means.

4. A mixture control for a fuel feeding system having control means and an induction passage, comprising means operable in response to variations in pressure differential between induction passage pressure and atmospheric pressure, means responsive solely to variations in atmospheric pressure, a lost motion connection between said means whereby said means may move a predetermined limited amount relative to each other and means adapted to connect one of said means to said control means.

References Cited in the file of this patent 

